Spring



Patented sept. 20, 1927.

sparire.

This invent-ibn relates ,t new and: useful improvements, in springs.;and. Particularly to coil springs usedinconnection with railway. cartrucks, alth'ough such Springs are One object ofthe invention is to,provide a coil spring of a giyen`length whichwill the length Vof travel,rthan springs hereto- Another object is to provide a springrof thischaracter which is formed vby coiling the stock on a mandrel, andwherein the stock is formed with a longitudinal flat portion on the sidenextk the mandrel, which permitsI the metal to expand into the body ofthe stock without theV usual ribs, which would prevent the fullcompression of the spring, and thereby shorten its length of trav-elwithin a given space.

Another object is to provide a coil spring` of this character whereineach convolution, in cross section, presents a greater transversedimension at the side next the mandrel, with the result .that when thespring is in operation the torsional strain on each individual coil willhave as its center the thicker side of the stock of the spring.

Other objects and advantages will be apparent from the followingdescription when taken in connection with the accompanying drawing.

In the drawing:

Figure 1 is a longitudinal sectional view of a spring made in accordancewith the present invention. t

Figure 2 is a transverse sectional view through the stock from which thespring is formed, before the stock has been wound on a mandrel.

Figure 3 is a similar sectional view after having been ywound on themandrel, and showing the position of the center of the torsional strainincident to the normal operation of the spring, when under compressionstrain.

Referring particularly to the accompanying drawing, there is shown acoil spring each convolution of which is tapered in cross section, withthe narrower portion lying at the outside of the spring, and the widerportion at the center of the spring. The narrow portion is representedby the numeral 10, and the wider portion by the numeral 11. It will befurther noted that the upper and lower faces of the convolutions areflat, thatltheirends are connected4 b y the curved portions gl 2 and 13,respectively. It will be further noted that -the curved, face 13 isformed with ',liat spot or stock from` which the spring is formed. i

I'n'xthe .use 'ofa coilspring 'in which the convolutions are7 circular.in` cross section, the

f tlme pf. @tht/...Springtoward fulll Compression, is limited by thebulging curved adj acent faces of the said convolutions. nThis isinconvenient when the spring must have a definite space in which totravel, and support or resist a great load. Attempts have heen made toremedy this feature by flat-tening the contacting faces of theconvolutions. lVheii, however, the stock is coiled on a mandrel, theportion of the stock next to the mandrel, will naturally spread, thusmak-ing the inner port-ions of the coils wider by the presence of riband thereby decreasing the length of travel of the spring. This isespecially noticeable where the ends of the cross sectional areas of theconvolutions are flat, as well as those which are arcuate. To overcomethis defect in the coiling of t-he spring, and to provide a spring whichwill have great resistance to a load, and yet have the maximum oftravel, within a given space,

I form a flat face throughout thelength of thestock of the spring,before coiling the sam-e on a mandrel. This fla-t face, which is shownat 14, is placed next to the mandrel. The curved portion of the stock.in which this flatface is formed, is wider than the portion at theopposite side of the coil, so that when the stock is coiled around themandrel, the expansion of the metal, due

` to the compression at the mandrel, will spread into the corners 15 and16, of the stock.

Vhen the spring is under compression strain, the individualcoiivolutions rotatev about an axis located at 17, which is in the widerportion of the coil turn. Thus the narrower side of the coil turnrotates or rocks on the said torsional axis at 17.

While I, have illustrated the fiat faces of the convolutions asconverging, with one of such faces at right angles to the longitudinalaxis of the spring, and the other oblique thereto, it will be understoodthat both of the said faces may be oblique to the axis of the spring,lthe principal result being in producing outwardly converging faces.

1. A coil spring each convolution of which has a cross sectional contourincluding opposite converging faces and opposite arcu` ate faces.

2. A coil spring each convolution of which has a cross sectional contourincluding opposite substantially flat faces and an arcuate face, saidarcuate face havingan in tern'iediate flat portion.u

3. A coil spring each convolution ot which has a cross` sectionalcontour including opposite substantially flat faces and opposite arcuatefaces, onc of the arcuate faces having an intermediate flat portion.

t. A coil spring each convolution of which has a cross sectional contourincluding opposite converging faces and opposite arcu ate faces, one ofthe arcuate faces having an intermediate flat portion.

5. A coil spring each convolution of which has a cross sectional contourincluding opposite substantially fiat converging faces and oppositearcuate faces.

In testimony whereof, I aix my signature.

ELMYR A. LAUGHLIN.

